As of May 1, 2014 the regulatory agency has received more than 4,800 reports of illness affecting a total of 5,600 dogs, 24 cats, and 3 people.

A number of reports came from owners with multiple dogs. More than 1,000 dogs have died. There have been 1,800 new cases of illness since the last FDA report in October 2013.

The FDA says the jerky treats were almost all manufactured in China, with flavors that include chicken, duck and sweet potato.

In 2013 the FDA distributed a request to veterinarians to share case information. From the responses, the FDA performed post-mortem examinations on 26 dogs.

Thirteen cases were eliminated and of the remaining 13 cases, an association with consumption of jerky pet treats could not be ruled out.

Eleven of these dogs had indications of kidney disease and two involved gastrointestinal disease

Among the reports, 60 percent of the animals were said to suffer from gastrointestinal and liver disease; 30 percent had kidney and urinary disease; and 10 percent of complaints filed involved various other symptoms including dermatological, neurological and immune system-related problems.

General symptoms of illness include decreased appetite, decreased activity, vomiting, diarrhea with blood or mucous, increased water drinking, and increased urination within hours of eating the treats.

In several analyzes, the snacks were found to contain low levels of antibiotics as well as the antiviral, FDA approved drug amantadine.

However, the FDA does not believe the illness was caused by amantadine because symptoms in the case reports are not typically associated with the drug.

The FDA emphasized though that amantadine should not be present at all in jerky pet treats, and the agency has notified the Chinese authorities that the presence of amantadine in these products is an adulterant.

Chinese authorities told the FDA that they will continue to perform additional screening and will follow up with jerky pet treat manufacturers.

FDA has notified the U.S. companies that market jerky pet treats found positive for amantadine of this finding and are testing both imported and domestic jerky pet treats for amantadine and other antivirals.

There have been many challenges along the way in the investigation. For one, symptoms of illness tend to be inconsistent from an animal to animal, reported CBS news.

Additionally, many pet owners often fail to take their sick dog to the vet right away and instead choose to monitor symptoms for a few days, reported CBS news.

The FDA says it has called upon the expertise of the Centers for Disease Control to to conduct further studies and research, reported CBS news.